Wiring system for automatic telephone-exchanges.



E. R. MGBERTY. WIRING SYSTEM FOR AUTOMATIC TELEPHONE EXCHANGES. APPLICATION FILED AUG.16. 1909,`

Patented Aug. 15, 1911,.`

-VVirnesseS 1. Frank R. MBertg Atty.

marron saisir, is Parana? onirica.

FRANK R. MCIBERTY, OF NEW RQ(II-EELLE,l NEW YORK, ASSIGNOR TO WESTERN ELEC- TRIC COMPANY, OF CHCAGQILLINOIS, A CRORATION 0F ILLINOIS.

` WRING SYSTEM -FOR AUTOMATIC TELEPHONE-EXCHANGES.

Specification of Letters Patent. Patented Alug, 15, 1911.

Application filed August 16, 1909. Serial No, 513,079.

To all whom it may concern: Be it known that I, FRANK R. MCBERTY, citizen of the UnitedStates, residing at New Rochelle, in the county of Testchestcr and \State of New York, have invented a certain new and useful Aimprorementin Wiring Systems for Automatic Telephone Exchanges, of 'which the followingbis a full, clear. concise, and exact description. y My invention relates to telephone exchange systems, and has for its objectxto preyent disturbances ot' telephonie communication by induction between the parallel conductors employed in the wiring of the switching Yapparatus thereof.

In an application for patent tiled by me February-27, i908, Serial No. llSdZl, there is described a cable in the form ot a tlat ribbon, the conductors of which are not twisted in pairs or triplets, as in ordinary telephone switchboard cables, butl lie parallel to one ai'iother'and therefore inapproximately the same plane. cables are used to wire in multiple the corresponding.; terminals of a. group ot autoniatie selectors, the cables being folded along diagonal lines and the conductors thereonc soldered to the selector terminals at alternate folds.

Ordinarily there are three terminalsin each selector and three conductors ot the cable associated with each metallic circuit telephone or trunk line. Two of these terminals and two of these conductors torni parts ot the two sides, respectively. ot one line circuit. ,The third terminal and third conductor for-in a part of a local or test circuit A'for the line. which circuit is usually' grounded either directly or through a battei-y. Each such i'iut ribbon cable contaii'iLA the conductors for -a plurality of lines and every three successive wires, counting' troni one edge of the cable to the other, comprise two line wires and one local or test wire. 'the v first and second, fourth and iitth, etc.. comprising pairs ot main circuit conductors, andthe third, sixth, etc.. comprisingjj local or test circuit conductors.` it will be readily understood by those skilled in the. art. thaty .a cable constructed of parulled conductors, such as this fiat ribbon cable. uhen used as a part ot, or when connected to tele phone circuits. 'would be particulaitly liable 'to inductive disturbances. causingr cross talk between the telephone circuits and noisy telephone lines. The reason ot this liabil- Such flat ribbon ity of inductive disturbances may be briefly explained as follows: In any two adjacent pairs of wires, say tlliosecomprising wires Nos. l, 2 and d. 5. respectively, ofa set of 60 six wires of such a cable, two of them, wires Q and 4., are nea-rer to each other than are the other two, l and'. l'llhe static induction between wires 2 and 4 is therefore greater than that between l and 5, and the resultI is cross talk, unless some means to equalize the induction is provided. Also at or near the edges of the cable, one wire of a pair, saywire 2, is closer to test wire 3 than is the other wire l ofthe pair, and the pair 'I0v is unsyinmetrically located with respect to the mass of other wires in the cable which are usually connected to ground. The static induction to ground therefore is un'- I equal as between the two wires of this pair, and ductuatingcurrents, which lare frequently induced in the exposed portion of a telephone line outside of the switchingstation would be stronger through one side of the line to `round than through ythe other, 80

the result being a noisy telephone line un less some means to equalize the induction is provided.

A type of selector adapted to be wired with fiat ribbon cables is one having a plurality of curved rows of terminals traversed by a plurality of brushes, one brush t'or each row. Preferably these selectors are arranged in vertical rows and the brushes are mounted on vertical spindles. Theflatribbon cables run vertically along straight rowsot terminals on each selector formed by corresponding terminals in successive curved rows, and the successive conductors ot each such cable respectively connect successiye terminals in a straight row on one selector with the corresponding terminals of other selectors in vert-ical alinement therewith. .i number of Vertical rows of' selectors makingup a `group are Wired in'lOO this manner, and each row preferably hasta connecting` rack at the top thereof. having terminals arranged in horizontal and vertical rows corresponding to the rows on a selector. The tlat ribbon cables terminate at verticz l rows on these racks. and the wires forming" extensions ot telephone lines and local circuits therefor extend horizontally along the horizontal rows ot terminals on the racks and connect in multiple the corresponding terminals of the. several racks associated with a gro p of selectors.

(Eil

Each selector ofthe type referred to has a. number of sets of three brushes each and the. brushes or" one set on any selector' are connected in multiple with the correspond- *ing brushes of the other sets thereon. ofill may be made 'through 'the selector to anyA "lane having terminals thereon.

When used in Aan automatic telephone exchange system, the brushes of such a selector preferably forni terminals ot a cornecting circuit adapted to be associated with a calling telephone line or a trunk line, and

.such connecting circuit usually includes a central source or current, which, when the lines are connected through the selector7 supplies current to the telephone transmitters at the substations or to other apparatus asso- .v'ith the connected lines.

This invention may be appl'ed toany telephone exchange system havingl sets or conductors lyingparallel to one another in approximately the saine plane and connecting the pairs ot line wires of metallic telephone circuits to 1the switchingapparatus. lt is, however, especially applicable to an auto* matic telephone exchange systein having groups of selectors arranged in rows, the terminals of which are wired by means of the parallel conductors in flat ribbon cables.

ln vgeneral, therefore, my invention provides that, in telephone exchange system, where two pairs of line wires are connected .to the switching,` apparatus thereof, each pair of wires by a pair ot' conductors in each ot' two sets of parallel conductors, the connection to the lino wires of one of saidpairs of conductors in one ot the sets shall be in reverse order to that of' the other-pairs in said sets. lt provides further that, where each` set of parallel conductors has more than 4two pairs of line conductors, as it would ordinarily in practice, the connections ofeach alternate pair in each alternate set or in one halt oi' the sets shall be reversed.

I ersing rows of terminals and are themselves arranged in rows, there being' at least one set or parallel conductors or cables for each row ci selectors. il? here tour such rows of selectors make up a group, my invention provides that a general reversal or transposition be in ade preferably in all of the pairs ot line wires between two of the sets ot conductors and the other two, and it is desirable that these last mentioned. reversals be so made as not to intertere with the balance between adjacent pairs secured by the lirst mentioned reversals. A static balance is thus secured in each metallic telephone circuit with respect to all other circuitsc'onnected to the cables `of parallel conductors as well as between adjacent pairs thereof.

y invention also provides for reversing or transposing the connections of certain of thcbrushes ot' the selectors, these reversals.

or ,'t-ranspositions corresponding to those of the cable conductors tot-he lines. This is in order that the flow of current by way of the brushes through the cable conductors to the lines shall in all cases be in the same direction.

l will describe my invention more particularly by reference to the .accompanying drawings, in which-- Figure l represents diagrammatcally and in an isometric view the wiring` of a group ot selector switches in an automatic telephone exchange system, and Fig. 2 represents in some detail, and in a similar view with parts broken away, the construction of a selector of the type ,which I prefer toq use.

ln the drawings S to S8 inclusive .are selectors arranged in four vertical rowsA, B, and D, and R" to. lt* inclusive are connecting racks, one at the top of each row of selectors. This apparatus may be located at the central otilce of a telephone exchange -tal curved rows of terminals as shown in Fig. 2, fined upon a cylindrical frame L and a row of brushes g to g. inclusive adapted lOt to traverse the curved rows of terminals I respectively. Corresponding terminals in the successive curved rows form straight rows running vertically, and I have represented one such vertical row on each selector by 'the terminals s to s inclusive.

im i 1,ooo,e 14 a series or spring latches c, one tor 'each set of three brushes, in such -a position that the brushes may rotate about the spindle z' without coming in contact withthe terminals. Springs f, one for each brush, bear against offsets ic of the brushes and tend to throw the brushes outwardly into position to make Contact with the terminals. oted on the spindle u and having offsets o, o, is controlled by an electromagnet w in such a manner that during the preliminary stage of movement of the brushes about the spinelle z', one or the other of the offsets o is brought into position to engage one of the s ring latches e and thus to release a set of t ree of the brushes.

inasmuch asvtliis invention does not involve the circuits by which thebrush selection is secured, nor the details of the selector mechanism, l have not shown in the drawings these circuits nor the complete selector. It will be apparent, however, t-hat the construction shown in Fig. 9. is one in which any one of two or more sets ot three brushes each may be selectively broughtl into position to engage the corresponding rows of terminals of the selector, the other setscotbrushes remaining out ot contactwith the terminals, although moving about the spindle with the first mentioned set of' brushes.

The pairs of line wires Z3 to Z10 lare represented as being connected inductively by way `of repeating coil windings to the brushes of the several selectors; a battery R being connected in each repeating coil circuit in a manner well understood by-those skilled in thc art. This battery is adapted to suppl)v current to line circuits which mayv be extended as shown to the various telephone substations. 4

Associated with each row of selectors is a set ot' parallel conductors. These areprct'- erably in the form ot' tiat ribbon cables 7e. l'n tact, there would be as many such cables for each row ot' selectors as there are vertical rows of terminals on one selector'. Having shown in Fig. l but a` single row of terminals on each selector. my drawing also shows but a single cable for each row. Each of these cables has as many conductors lying parallel to one another as there are terminals in a vertical row on one selector, and therefore six conductors in the arrangement shown inthe drawing. Conductors mi', m2 and mf are associated with one telephone line and conductors m4, mi and in with another line. nl and mi form a pair of line circult conductors. lmi' a local cirline conductors, and la another local circuit conductor. These six conductors in each cable respectively unite in multiple corresponding terminals of the selectors in one vertical row and connect them with ter- An arm g pivthe extension of line Z2 being representedv by a pair o', b2. A local circuit wire a3 is associated With'line Z and a local circuit- Wire b is likewiseassociated with line Z2. Terminals r to r inclusive of the several connecting racks are united in multiple by these wires a', a2, a, Z2', b2, b3, whichl are preferably made up` in twisted triples for each telephone line; thus a', a2 and a3 would comprise one twisted triple and b, be and 53 another.

The method of' making the connections of theline wires to the terminals of the connecting racks in accordance with my invention is as follows: At terminals r4, 75 of connect-ing rack R3, line wires Z1 and ZF of line Z2 are'connected in reverse order to that of the same wires tol terminals 'r4 and T5 of connecting rack R4; that is, wire b is connected to terminal r* of rackR4 and toterminal 1'5 offracl: R3, and in like manner wire b2 is connected to4 terminal @of rack R4 and to terminal r4 of rack R3. reversal in the order of connections of the pair Z occurs atconnecting rack R; Line wires a and (L2 of line Z, however, are connected without a reversal as between connecting racks R3 and R4, and as between racks R and R2. By means of these reversals the adjacent Vpairs of conductors in the fiat ribbon cables are transposed in relative'positions to one another in -the different cables with the result that induction .nections of all of the line wires to lthe'pairs in the cable conductors. Such reversals are indicated at and 1/ in the pairs of wires a, u2 and b, b2, midway between connecting racks R and R4 on one' side and R and t2 on the other. It will be noted that these reversals do not disturb the balance between lines Z and Z2 secured by the reversals at terminals r4 and rf of connecting racks R3 and R.

As it is desirable to have the fiow cf cur-V rent in the several lines of the exchange i always in the same direction regardless of cuit conductor, ym4 and m" another pair of" which selector is used to make the connection thereto, a rei'ersal in the order of coneetion or transposition is made in the conductors or wires leading from certain pairs of brushes to the battery in the connecting circuit and such reversals or transpositions A like` are made wherever the corresponding terminals of the selectors are transposed by rea- 'xson lot' their connection'- to the transposed.

)conductors in the fiat ribbon cables it will lI be noted that no transposition is required in 'the selectors in row D; that in row B the n ections'at is made-to correspond to the transpositions at :v and y; that, in the selectors of rows C and A the lower pairs of brushes g4, g5 are transposed at s and' e2 with respect to the uppenpairs g', 02, these transpesitions -corresponding to the reversal of connections at terminals and r? .of connecting racks R and R8; while at the selectors in row A a general reversal of the battery connections at 002 is also made to correspond to the 't anspositions at and y.

A brief summary may be made of the several reversals or transpositionsin the cabling system shown in thedrawing made in accordance with my invention and the advantageous results thereof The reversals at terminals rt and ijs of connecting racks R and R3 prevent cross tall; between the telephonelinestl and Z2) which have adjacent pairs of conductors in the dat ribbon cables;

thosefat .and y prevent the lines from being noisyand'those at fr?, z and z2 insure a uni-directional flow of current in the telephone lines. f

Although l have shown for the sake of clearness a separate battery in each connecting circuit, it is to be understood that one battery may be used'and would ordiin a row connected in the same way those` shown by 4the iiat 'ribbon cables 7c; that any suit-able number ot rows oi' selectors may be provided in a group and that each selector may vhave as many terminals as practical requirements dictate. l have shown but two lines connected to terminals of the connecting racks and selectors, lout it is to be understood thatl other telephone lines may be connected to other terminals in the same manner and that in the case of a large number ot lines7 the pairs oi line wires that are counected to alternate pairs of termimils in vertical rows lon the connecting. racks and thus to alternatepairs ot' parallel conductors in the iiat cableswould be transposed. at alternate connecting racks. Obviously the brushes of the several selectors may be connected to telephone lines either directly 'or indirectly through trunkor connecting circuits.

` .As this invention is not concerned with the details of circuit arrangements, only so much of the wiring is shown as seems necessary to fully describe the invention. For

niet

and corresponding signs placed near the wires Qt the lines l and Z2 indicate the direction of currenthin the lines when the battery is connected therewith through the selectors and caile conductors.

What l". clainiisz t 1. in a telephone exchange system, the combination with two pairs of line wires forming in part two metallic telephone circuits respectively, and switching` mechanism adapted to extend the circuit of said line wires to other iines, oit two sets of parallel conductors ea'cli set comprising two pairs ot' conductors connecting said switching mechanism in circuit with said two pairs oi line wires respectii'ely, one of said pairs of condiixctors in one of the sets being connected in circuit. in reverse order to that of the other pairs in said sets, whereby cross talk between said telephone lines is prevented.

2. in a teicjhone exchange system, the combination with' two pairs of line wires forming in part, two metallic telephone circuits respectivel and two sets of switches each'adapted to 'tend 'the circuits of said two pairs of line wiresto other lines, of two setso parailel conductors one associated with each set oit switches4` each set oconductors comprising two pairs connecting one of said setsiof switches in circuit with said two pairs oi? .line wires respectively. one of the pairs ot conductors in one oi the sets being connected in circuit in reverse order to that oit the other pairs in said sets, whereby cross tall; between said telephone lines is i prevented 3. Yin a telephone exchange s vstem, the combination with two pairs of line wires forming in part two metallic telephone circuits respectively, two switching mecharnis'ms and a source ot current. cach of said switching mechanisms being adapted to connect said source 'of current to either of said pairs of line wires, of two sets ot parallel conductors, one associated with cach switching` mechanism. each set comprising two pairs of 'conductors connecting one of saidA combination with two pairs of line wires forming` in part 'two metallic telephone circuits respectively and two selectors, each selector having a row ot' terminals for said lines, of two sets of conductors one for each selector, each set having its conductors lying parallel to one another in approximately the same plane and comprising two pairs respectively connecting said two pairs or" line wires with the terminals ot one of said selectors, one of the pairs oi conductors in oneiof the sets being connected in. circuit in reverse order to that of the other. pairs in Y said sets, whereby cross talk between the telephone lines is prevented.

5. In atelephone exchange system, the combination with two pairs of line wires forming in part two metallic telephone'circuits respectively, and two selectors, each Selector having terminals. tor said lines arranged in a row `and two pairs of current connectingbrushes adapted, respectively, to make contact with said terminals, ot' two Sets of conductors one for each selector, each set having its conductors lying` parallel to ,one another and comprising two pairs res ctively uniting the terminals ot' one of tli selectors with said two pairs of line wires, one of the pairs of conductors in one of the sets being connected in circuit in re- Verse order to that ot the other pairs in said sets, and the pair of said brushes or' one selector whichis adapted to make contact with the. pair of terminals that are connected in circuit'through the rcversely connected pair of conductors being connected in circuit likewise in reverse order to that ot the other of said pairs ot .brushes of said selectors, whereby cross talk between the telephone lines is prevented..

6. In al telephone exchange system, the combination with two pairs ot line wires forming in part two metallic telephone circuits respectively and switching mechanism therefor, of two ribbon cables each having its conductors lying parallel to one another and comprising two pairs, respectively, connecting said two pairs ot line wires with said switching mechanism, one of said pairs of conductors in one of the cables being connected in circuit in reverse order to that of the other pairs in said cables, whereby cross talk between the telephone lines is prevented.

7. In a telephone exchange system., the combination with two pairs ot' line wires forming in part two metallic telephone circuits and two selectors, each selector having a row ot' terminals tor said lines, in combination with two ribbon cables one for each selector, each-cable having its conductors lying parallel to one another and comprising two pairs respectively uniting said two pairs of line wires withtheterminals of one of said selectors, one of the pairspf "c "muiluctors in one ot the cables being connected in circuit in reverse order to that of the other pairs in said cables, whereby cross talk between the telephone lines is prevented.

8. in a telephone exchange system, the combination with two pairs ot line wires forming in part two metallic telephone circuits, a source of current and two rows of selectors, each selector having terminals for said lines and two pairs of current connecting brushesadapted to make contact with said terminals respectively and thereby con nect said source ot current/in circuitwith said pairs of line wires, of two ribbon cables one for each row of selectors, each'cable4 having its conductors lying parallel to one another and comprising two pairs uniting in multiple the corresponding terminals of the selectors in one row and being respectively connected in circuit with said pairs of line wires, one of' said pairs of conductors in one of the cables being connected in circuit in reverse order to that of the other pairs in said cables, and the pairs of brushes in one of the rows of selectors which are adapted to connect said source of current in circuit through the reversely connected pair of conductors being connected to said source of current likewise in reverse order to that of the other pairs of brushes of said selectors.

9. ln a telephone exchange system, the combination with two pairs of line wires forming in part two metallic telephone circuits respectively7 two rows of selectors each selector having tour terminals for said line wires and two pairs ot' current connecting brushes adapted to make contact with said terminals respectively, and two connecting racks one for each row ot selectors each connecting rack having four terminals corresponding to those of a selector, of two ribbon cables one for each row of selectors, each cable. having four conductors lying parallel to one another and comprising two pairs uniting in multiple the corresponding terminals ot the selectors inone row and the connecting rack therefor, the corresponding terminals of said two connecting racks being connectedtogether by said pairs of line wires, the connections of one of'said pairs of line wires to the terminals on one of the connecting racks being in reverse order to that of the other connections ot said pairs of line wires, and the pairs of brushes in one of the rows of selectors which are adapted to connect current in said circuitsthrough the reversely connected pair of connecting rack terminals being connected to the poles ot a source of current likewise in reverse order to that ot the other pairs ot' brushes of said selectors.

10. ln a telephone exchange system, the combination `with a plurality ot selectors `each having a row of terminals and a row 

